Skilled archers are constantly seeking bows that are lighter, stronger, steadier, and easier to use. To this end, bow manufacturers have produced a wide array of technological advancements to improve the archer's accuracy, precision, and target view during a shot. For example, as a result of a growing trend for overall mass reduction in bows, bow risers are made light and easy to carry by being formed with a thin skeletal structure and may have a sight window to assist the archer's aim.
The sight window of a typical riser is a portion of the riser that is laterally offset from a neutral axis that runs vertically through the connection points of the limbs to the riser. Risers with a sight window do not directly obstruct the archer's vision of the plane or area through which the arrow will be launched, so he or she may have a better view of the target. Bow sights may also be positioned in the sight window to assist the archer's aim.
Despite these advantages, implementing a sight window usually also has drawbacks for the archer, especially when the riser has the aforementioned thin structural members. At some point, weight of the riser can no longer be reduced without exceeding the material's yield stress capability and allowing unwanted bending of the riser. Because the sight window is offset from the neutral axis of the bow, tension applied to the riser while drawing the bow may twist or bend the riser at the sight window toward the neutral axis at transition portions of the riser where the riser is laterally offset. The tension and torque must be countered by the archer's grip to keep the bow in equilibrium, so when the bowstring is released, the bow may be torqued or jump in the archer's grip as the tension in the limbs is released. These reactive motions of the bow may reduce accuracy, increase vibration, and deflect arrow flight. There is therefore a need for improvements in bow risers that provide stiffness at the sight window while minimizing twisting and bending through the cycle of draw and release while still providing light and reliable riser structure.